- record all the species present
- the temperature
- test for nitrates, phosphates and other minerals
The results for this investigation were obtained by following the method below.
A sample off water was collected in a sample tray. The sampling net was placed in the water against the current and moved in a joggled motion, ensuring to dislodge as many samples of as many species as possible. The kick search method may also be used in shallow water with a fast current (castle acre). After the sample was collected, it was carried up to the tray and the contents emptied into the tray. The thermometer was then place into the tray and the temperature recorded. The species in the tray were then identified and their frequency recorded. The flow rate was then measured by selecting a 5 meter measuring how long it takes for a stick or debris it cover that area. The flow rate was then measured using the equation:
Speed = Distance
Time
This method of measuring the flow rate is not very accurate so considerations must be taken into account when looking at the results.
Chemical tests were also carried out at each site to measure the pH and all other organic compounds found in the river. To measure the pH you need to take a sample of water and add a universal indicator. Measure the colour the water turns against the chart on the box this will give you the pH of the water.
The procedure was repeated for the four other sites.
Equipment list
Sample tray
Sampling Net
Thermometer
Various Chemical test kits
Methyleneblue
Method
The results for this investigation were obtained by using the following procedure.
A sample off water was collected in a sample tray. The sampling net was placed in the water against the current and moved in a joggled motion, ensuring to dislodge as many species as possible. The kick search method was used in shallow water with a fast current (castle acre). After the sample was collected, it was carried up to the tray and the contents emptied into the tray by inverting the net. The thermometer was then place into the tray and the temperature recorded. The species in the tray were then identified and their frequency recorded. The flow rate was then measured by selecting a 5 meter section of the river measuring how long it takes for a stick or debris it cover that area.
The flow rate was then measured using the equation:
Speed = Distance
Time
Chemical tests were also carried out at each site to measure the pH and all other organic compounds found in the river.
To measure the pH you need to take a sample of water and add a universal indicator. Measure the colour the water turns against the chart on the box this will give you the pH of the water.
To measure the biological oxygen demand i.e. the requirement of oxygen by living things in the water, you follow this procedure:
Add a sample of the water to the universal indicator
Methyleneblue which will turn blue in the presence of oxygen. Add a stopper and place in a cupboard until the solution turns skyblue. The quicker the solution turns sky blue the higher the oxygen content.
The procedure was repeated for the three other sites.
Results
Species results
KEY
Trent Biotic Index
The letters stand foe the number of times the TBI was taken at that site of the river.
The Trent biotic index shows you the amount of pollution there is in a sample of water. The closer the number to 10 the better the quality water. The closer the number to 0 the poorer the water this means that very polluted and therefore is no oxygen in the sample and therefore less species diversity.
It is a simple method, which determines the pollution level by the presence/absence of certain invertebrates.
The diagram will not be submitted as I have completed another one on graph paper. I just cannot delete it!
Environmental table
This table shows the relative amounts of organic compounds found in the water and also shows the different environmental conditions at each different site. The chemicals were tested for using chemical test kits.
Discussion
The Trent biotic index is preferred over using a chemical test because a chemical test is too time consuming and more expensive. The Trent biotic index takes on a long-term view of what the water is like and a chemical test show only a snapshot of what the water is like at that moment of time. Because the river is situated near and industrial site there is a possibility of chemical pollution but due to the movement of water by the time the sample for the chemical test is taken the chemicals my have already been washes away. Therefore the results obtained may not show a true reflection of the amounts of chemicals contained in the river. Also different times of the day will result in different flow rates and therefore different amounts of chemicals at one moment of time.
At the first kings Lynn site the water was acidic due the pollution of heavy metals and road surface pollution injected into the river by the industrial sites. The acid reacts with the calcium carbonate, which results in the neutralisation of water. The reaction reduces the amount of calcium carbonate in the water, which results in the fewer species found that are dependent on calcium carbonate to build exoskeletons. Therefore this leads to a decrease in species diversity. As shown by the species results table. The pH results shoe that the water is slightly below neutral at 6.5.
At the second kings Lynn site there is a lower oxygen level due to the presence of surface algae which use up the oxygen during respiration but a higher demand for oxygen by any species that are trying to survive in those conditions. The supply of oxygen does not meet the demand therefore the invertebrates that rely on high oxygen content to survive they will die off for example stonefly nymph. Invertebrates who can tolerate a low oxygen content will be found in this section of the river. Due too an increase in the amount of algae there will be competition for the already depleted amount of oxygen. This will lead to a decrease in the amount of species present.
The third site on the river Nar, High Bridge, has a high concentration of organic material from the fertilisers and the pesticides applied to the surrounding fields. Not all organic material is harmful in the right amounts. However this site has very high amounts of organic compounds when compared to the others. This could lead to an increase in populations of detritivors, which would lead to an increase in the populations of carnivore. An increase in the numbers of species present will lead to an decrease in the amount of oxygen therefore the species will gradually disappear starting from stonefly nymph. Large amounts of nitrates and phosphates will lead to an increase in the growth rate of plants especially algae which do not allow light to penetrate and eventually lead to a decrease in the amount of oxygen in the water.
The final site visit on the river Nar was castle acre. Of all the sites this one has the fastest flow rate. Only species with sufficient anchorage mechanisms will be able too survive in this section of the river for example shrimp. Also due to the movement of water there will be a higher concentration of oxygen. There will therefore be an increase in the number of species, which require a higher concentration of oxygen for example stone fly nymph and a decrease in the amount of smaller species that have a lower demand for oxygen for example Tubifex worm.
Chi squared test,
Null hypothesis: there is no pattern to the distribution of shrimp
along the course of the river.
I =
Degree of freedom =
Critical value at 5% =
The sample of shrimp was taken because it is a species that is adapted to living where there is a high concentration of oxygen.
The null hypothesis was disproved. The results obtained showed that there was a pattern in the distribution of shrimp along the river. It showed that the shrimp was most abundant where the environmental conditions were best suited to its adaptations. It is best adapted for conditions where there is an abundance of oxygen and a constant supply of calcium carbonate.
The first kings Lynn site has a lack of chalk this means that organisms that depend on chalk for the development of their exoskeletons will be present in low numbers. The site water is brackish due to the seawater that enters through the sluice gate. This creates osmotic problems for the freshwater species. Therefore there may be less of these species present or they may have to adapt to the continuously varying habitats. The species may not be able to find their niche and this may result in a reduction on the overall population of different species.
The second kings Lynn site. This site does not have any tidal influence therefore there will be no flow rate therefore less oxygen present. No flow rate means less oxygen there for fewer species will survive due to a lack of oxygen of respiration. The presence of algae also mans that there competition for any oxygen that is present the water there is also competition for light. Also the pollution from the road surface and industry builds up these factors lead to an overall decrease in species diversity. This may be due to he oxygen being used up in chemical reactions
The third site on the river Nar High Bridge is periodically cleaned therefore part of the surrounding vegetation and silt is removed. This means that the species habitat is not stable. This will mean no continuous changes for the species present. Some invertebrate may not be able to cope with these changes of their habitat and therefore they may start to die off. Over a number of years this will lead to a decrease in the species diversity. If there is less vegetation there is less oxygen due to decrease in the amount of photosynthesis, less food for the vertebrates and less shelter therefore there will be fewer species present.
The final site is Castle Acre this site is alkaline there is more species with a calcium carbonate exoskeleton present. The populations of these species will increase therefore there is greater species diversity. The section of river is also relatively shallow therefore more light can penetrate and more photosynthesis can occur and therefor there is a greater amount of oxygen present in the water.
It has the fastest flow rate of all the sites investigated. Therefore the species that rely on surface tension will be swept away and this will lead to a decrease in the species diversity.
These samples where taken around June. This will affect the samples present because there will be different flow rates due to the different amounts of rainfall. The flow rate will be slower at this time of year as there is less rain, the species diversity will therefore increase. A wider amount of species will be present.
The results I obtained from using Trent Biotic index indicate a pattern. They show that the more pollution present the lower the range of different species present. This is evident in the result obtained for the second kings Lynn site on the river Nar. The Trent biotic index for this site had an average of 2, which indicates that not many species can survive in the water due to less oxygen present in the water. There are also fewer plants present, which will eventually lead to less species diversity. However these conditions promote the growth of algae turns the water green and depletes the oxygen content.
On a particular site some caddisfly larva was found in an unfamiliar environment. This may be due to it being swept upstream by the current.
The areas of this investigation that may be improved upon include the following. When taking samples we sampled from the edge of the river, we could improve this by going into the middle of the river on all three sites and also take samples from three different sites in that section of the river. Repeating the investigation a couple of times would also make your results more accurate. Using a flow meter would also make the measurement of the flow rate more accurate.
Conclusion
The results of my investigation agree with my hypothesis. They show that the environmental conditions do change along the river and that these changing conditions do have an effect on the species diversity. The results showed that the most diversity was found at the site which had the most average conditions, this was at kings Lynn site 2 which had an intermediate flow rate slightly acidic pH, low levels of pollution, a good oxygen content and a high temperature. The species may not have been in abundance but they were present.
The least diversity was found in the site where there was a low oxygen content, no flow rate. However some factors were directly more influential then others. I fell that the oxygen content and the flow rate were most influential in determining the species diversity.